The UK Government must provide funding to cover the healthcare costs of prisoners in the 2,100-inmate super-prison planned for North Wales, it was demanded yesterday.

Fears have been raised about the true costs of the £200m-plus project following claims that cash from the UK Government is failing to cover the cost of existing prisoner healthcare services.

An investigation by Cardiff University’s Wales Governance Centre found that in 2012-13 the Welsh Government received £2.5m from the UK Government for prisoner healthcare. The sum reached £3.4m when Welsh Government cash was added.

But the research shows the total cost of primary healthcare for the three public prisons in Wales – HMP Cardiff, HMP Swansea and HMP Usk – was £3.9m.

According to the Ministry of Justice website, the three prisons have a combined capacity of 1,502 and there is concern about the impact of Wales’ prisoner population growing by a further 2,100.

It has been claimed the number of Welsh prisoners in Wrexham could be as low as 500. MPs have called for action to ensure that proper funding is provided so that local services can meet what could be a multi-million pound hike in costs.

Academics are now calling on Welsh politicians to “properly scrutinise” the impact of the facility, arguing it will be “the second biggest prison in western Europe”.

Robert Jones, a research associate at the Wales Governance Centre at Cardiff University, said: “This research shows that even before the Wrexham ‘super’ prison has been built, prisoner healthcare in Wales is already being underfunded. The fact that the Welsh Government does not hold information on the costs of prisoner healthcare in Wales raises some very real questions over the extent to which such services are being effectively scrutinised and accounted for.”

A Welsh Government spokesman said: “We are unable to comment on findings of a report we have yet to consider in detail. However, the devolved settlement in relation to healthcare in the public sector prison estate was agreed with the UK Government in 2003.

“Inflation and some additional increases in staff costs has resulted in the need for us to provide additional healthcare resources for the prison estate to assure quality services are provided to prisoners. The responsibility to meet these healthcare costs falls to the relevant health boards.

“Arrangements are in place for key partners, including the Welsh Government, NHS, NOMS, the Ministry of Justice, and the UK Treasury to closely scrutinise the potential impact and costs in North Wales of the proposed new prison being built in Wrexham on the Welsh NHS.”

The responsibility for health services in public sector prisons in Wales was transferred from the Home Office to the Welsh Assembly Government in April 2003. Three years later, this responsibility was devolved to Local Health Boards (LHBs).

Plaid Cymru Westminster leader Elfyn Llwyd said: “I think it’s a genuinely concerning thing because here’s another example of why we do not need this prison facility for North Wales. [It] is there in order to import people from other parts of the UK...

“I’ve yet to see any argument in favour of this prison, to be honest.”

He added: “Obviously, the UK Government are sending an allocation down and it’s nowhere near enough. Every conceivable way you look at this prison, it’s doomed to failure... If it has to go ahead then of course the allocation must follow it because otherwise once again the Welsh Government are being underfunded and that’s not good enough.”

Wrexham Labour MP Ian Lucas said: “One of the major issues that I’m working on addressing is looking at the implications of the placement of the prison and what additional resources will be required by the local NHS, by the local authority and by local institutions generally to service what is going to be the largest prison in the United Kingdom – 2,100 prisoners and probably around a quarter of those are going to be from North Wales and three-quarters are going to be from different parts of England...

“I think it’s imperative that we ensure that the resourcing follows the prisoners from wherever they come from. For what is essentially an England and Wales project, we will need to have an appropriate level of funding so the funding doesn’t fall entirely on the local health board. That’s the sort of area I’m exploring and has to be looked at now.”